The Ishtar Gate was constructed as the final gate in the city of Babylon and was associated with the gods and cosmology of the Babylonian culture. The road before and after the Ishtar Gate was known as the Road of the Gods or the Processional Way and was where the annual New Years party was celebrated every year.

Construction

Ishtar Gate Drawing

"I [Nebuchadnezzar II] laid the foundation of the gates down to the ground water level and had them built out of pure blue stone. Upon the walls in the inner room of the gate are bulls and dragons and thus I magnificently adorned them with luxurious splendor for all mankind to behold in awe."

Inscription of Nebuchadnezzar II at the Ishtar Gate

Blue Glazing

The unique blue glazed bricks of the Ishtar Gate are a wonder in and of themselves. For many years no one has known how these bricks could have gotten this beautiful coating until modern archaeologists ran the material through spectral analysis. From there it was proven that the material was made from a combination of many rare materials not normally found in Babylon. In fact, some of the materials were imported from the furthest reaches of the known world at the time, so it is clear this was an important process to them. So how exactly were these bricks made?

Ishtar Gate Relief

Well a chemist named Stefan Fitz solved the mystery and found the ancient process involved in making these bricks. The first and most important step involved mixing up a specific substance made of sand and soda ash which was made from vegetable ash. This substance was then kiln-fired at a specific temperature of 900° C to create a type of glass that would form the basis for the glaze. To this day no one knows how they measured and kept the temperature constant in order to bake these bricks.

The glass that was produced was ground into a fine powder and small quantities of cobalt and copper-oxide were added to give the unique blue color. What puzzles archaeologists further is how they measured such precise quantities that are accurate to the milligram when we only recently got that technology with electronic scales. Distilled water is finally added and this turns the powder into a creamy liquid that forms the glaze for the bricks. The glaze would then be painted on the brick and re-fired in a kiln for 12 hours at a constant temperature of over 1000° C.

The ancient Babylonians were masters of this brick producing process and the Ishtar Gate alone contains over 20,000 of these magnificently decorated bricks. They may have also been used in other construction projects as well. It should be noted how much scientific knowledge and effort is involved in this production process. The glazing of these bricks is a remarkable feat in and of itself.